The present invention relates to a damper for a steering wheel assembly.
Most steering wheels require a mass damper to dampen the vibration of a steering wheel, which may vibrate as a consequence of road conditions. The mass damper serves to reduce or eliminate vibration of the steering wheel for an anticipated range of frequencies. A mass damper, however, is expensive and requires space inside the limited room offered by a steering wheel assembly. Moreover, the mass damper increases the total mass of the steering wheel.
Driver side airbag modules are located in the limited space offered by the steering wheel assembly. The airbag module may comprise an airbag, airbag housing, and airbag inflator as a single unit installed within the steering wheel assembly. It has been suggested to use the airbag inflator as the mass damper for the steering wheel. However, the use of the airbag inflator as a damper presents challenges. One such challenge is preventing the leakage of gas from the inflator into the passenger compartment during deployment of the airbag. This gas is typically hot, and it would be undesirable to release the gas into this compartment.
There is therefore a need to use the airbag inflator as a mass damper while still preventing the leakage of gas from the airbag housing into the passenger compartment.
The present invention comprises a steering wheel assembly that uses an airbag inflator as a mass damper. An airbag is stored in an airbag housing. The housing is spaced from the airbag inflator to permit the free movement of the inflator relative to the steering wheel, thereby permitting the inflator to act as a mass damper. As a consequence of this spacing, a gap between the airbag inflator and the airbag housing exists. Upon activating of the airbag inflator, a shield bridges the gap between the airbag inflator and the airbag housing, directing the gas from the inflator to the airbag and preventing the gas"" escape into the passenger compartment.
The shield may deform from the pressure of the escaping gas from the airbag inflator and, by deforming, bridge the gap between the airbag inflator and the airbag housing. The shield may comprise a ring having overlapping segments to promote deformation. In addition, the shield may comprise two layers with one layer folded over a portion of the other layer to provide additional protection against the escape of gas.
In this way, the shield may serve to seal a gap between the airbag housing and the airbag inflator. Thus, during normal operation of the vehicle, the shield is drawn away from the gap to permit the free movement of the airbag inflator. Upon activation of the airbag inflator, the shield closes the gap. Accordingly, the airbag inflator may be supported to move freely relative to the steering wheel and thus damp its vibration by a resilient connection to the steering wheel. The airbag inflator may be tuned to damp a range of vibration frequencies of the steering wheel so as to limit steering wheel vibration.